A frantic search is underway in California for a 29-year-old Uber and Lyft driver who disappeared, and they're asking for the public's help to find him.

Joshua Thiede was last seen at 11:30 a.m. Sunday, February 11, on Wilshire Boulevard in the city of Los Angeles, according to the LAPD's Missing Persons Unit.

Thiede is described as white with brown hair and blue eyes. He stands 6 feet tall and weighs around 170 pounds.

It is unknown what he was wearing, but he was driving for Uber and Lyft in a four-door 2014 black Nissan Altima with the California license plate #7CSD450, police said.

A generic image of a black 2014 Nissan Altima, which was the type of vehicle driven by missing man Joshua Thiede.

Thiede has not been seen or heard from since, and his family is concerned for his safety, according to authorities.

His mother, Janet Thiede, tweeted out Saturday that according to her family usage cellphone plan, her son or someone using his phone called 911 on Feb. 12 and then hung up.

"This doesn't feel right. Honestly, it didn't really feel real to me until after the news stations started calling," friend Yokeena Jamar said. "The 911 phone call was made on Monday at 2:30 p.m. We're not sure why he made that phone call. There was no transcript of that phone call because they did not record it. It was a hang-up call."

Other friends said Thiede was working on a shoe line that would benefit the homeless and he would never just disappear.

Jamar said Thiede would tell at least his sisters or his mother that he would be going somewhere.

His phone's last pings were in two locations in a Pico-Union neighborhood, not far from where he was last seen. But since then, his phone has either been turned off or died.

"The phone moved from Tuesday night to Wednesday night from another location in this area. So we're concerned that maybe some foul play is involved," Jamar said.

A spokesperson for Uber said they are aware of the situation and are working with the LAPD.

Lyft issued a statement saying, "Our concern is with Mr. Thiede's safety and wellbeing. We have been in touch with his family and law enforcement and will continue to assist in whatever way we can."

Anyone with information is urged to contact the Missing Persons Unit at (213) 996-1800. During non-business hours or on weekends, calls should be directed to 1-877-LAPD-24-7.